Maturation of rhesus monkey oocytes in chemically defined culture media and their functional assessment by IVF and embryo development

This study compared success of in-vitro maturation of rhesus monkey oocytes in protein-free versus serum-containing culture systems, assessed by embryo development subsequent to IVF. Four media were tested: (i) modified Connaught Medical Research Laboratories medium (mCMRL-1066); (ii) hamster embryo culture medium-10 (HECM-10); (iii) control: mCMRL-1066 + 20% bovine calf serum (BCS); (iv) HECM-10 + 20% BCS, Immature oocytes from FSH-stimulated rhesus monkeys were allocated among the media containing ovine FSH (5 mug/ml) and LH (10 mug/ml) and cultured for 36-40 h. Metaphase II ova were inseminated and putative zygotes were cultured in mCMRL-1066 + 20% BCS until development arrested. Ova matured in all four media had similar (P > 0.05) potential to initiate (66, 67, 82 and 69% respectively) and complete meiotic maturation (60, 50, 76 and 57% respectively). Inseminated ova in all groups had similar potential to be fertilized (86, 83, 84 and 90% respectively), cleave (71, 83, 76 and 90% respectively) and develop to the blastocyst stage (19, 17, 16 and 30% respectively). These results indicate for the first time that primate oocytes can be successfully matured in protein-free medium, with subsequent blastocyst development, comparable to responses in complex medium with serum. This finding will facilitate studies on mechanisms regulating primate oocyte maturation.